Anatomy Final 3

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Anatomy Final 3
2010-12-14 02:48:39
Anatomy Final Guide

Chapters 12-20 from Study Guide only
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  1. Nervous Tissue
    1. neurons: excitable nerve cells that transmit electrical signals

    2. neuroglia: nonexcitable supporting cells that surround and wrap neurons

    **both develop from same embryonic tissues: neural tube and neural crest

    Basic Structural Units of the Nervous System

    • Characteristics of Neurons
    • 1. Highly Specialized cells that conduct electrical signals (nerve impulses; action potentials)
    • 2. Extreme Longevity: neurons can live and function for a lifetime; over 100 years
    • 3. Do Not Divide: neurons lose their ability to undergo mitosis; cannot be replaced if destroyed (except neural stem cells in some areas of the CNS)
    • 4. High Metabolic Rate: requires continuous and abundant supplies of oxygen and glucose

    Supporting Cells (Neuroglia)

    • Neuroglia or glial cells
    • six types of glial cells: four in the CNS, two in the PNS

    • Neuroglia in the CNS
    • (nuclei of neuroglia stain darker than neurons)Outnumber neurons 10 to 1; make up ~half brain mass
    • *can divide throughout life

    • astrocytes: star-shaped; most abundant type in the CNS; have radiating processes with bulbous ends that cling to neurons or capillaries
    • functions:
    • 1. regulating NT levels by increasing rate of uptake
    • 2. signaling increased blood flow in active regions
    • 3. controlling the ionic environment around neuronshelp synapses form in developing neural tissue; produce molecules necessary from neural growth; propagate calcium signals that may be involved in memory

    microglia: smallest and least abundant type in CNS; have elongated cell bodies and processes with many projections; are phagocytes the "macrophages of the CNS": migrate to and engulf invading microorganisms and injured/dead neurons; derived from blood cells (monocytes)

    Ependymal cells: form a simple epithelium lining the central cavity of the spinal cord and brain; bear cilia that help circulate the cerebrospinal fluid

    oligodendrocytes: have fewer branches than astrocytes; line up in small groups and wrap cell processes around thicker axons in the CNS, producing insulating myelin sheaths

    • Neuroglia in the PNS
    • satellite cells: surround neuron cell bodies within ganglia
    • schwann cells: surround all axons in the PNS, forming myelin sheaths
  2. The Spinal Cord
    • Functions:
    • 1. attachment of spinal nerves; involved in sensory and motor innervation of the entire body inferior to the head
    • 2. provides a two way conduction pathway for signals between the body and the brain
    • 3. it is a major center for reflexes

    • Location:
    • Extends from foramen magnum to the level of the first or second lumbar vertebra (L1 or L2)

    • Gross Anatomy
    • Conus Medullaris: tapered inferior end, "cone of the spinal cord"
    • Filum Terminale: long filament of connective tissue tapering from the conus medullaris; attaches inferiorly to the coccyx and anchors the spinal cord
    • Cervical and Lumbar Enlargements: enlarged sections of the spinal cord where the nerves of the upper and lower limbs arise
    • Cauda equina: collection of nerve roots at the inferior end of the vertebral canal; descending lumbar and sacral nerve roots
  3. Embryonic Development of the Brain
    • During Week 4 of Development,
    • Primary brain vesicles appear at week 5, secondary brain vesicles form (adult brain structures)

    • 1. Prosencephalon (forebrain) divides into
    • telencephalon (cerebrum: cerebral cortex, white matter, basal nuclei) and diencephalon (thalamus, hypothalamus, epithalamus; retina)

    2. Mesencephalon (midbrain) remains undivided (becomes brain stem: midbrain)

    3. Rhombencephalon (hindbrain) divides into the metencephalon (brain stem: pons; cerebellum) and the myelencephalon (brain stem: medulla oblongata)

    Adult brain divided into four regions: Cerebrum, Diencephalon, Brain Stem, Cerebellum

    • Gray and White Matter in the brain:
    • Gray matter: outlines inner surfaces, surrounding ventricles, also on outer cortex of cerebrum and cerebellum
  4. Cranial Nerves
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    • 1. Olfactory Nerves: sensory; smell
    • 2. Optic Nerves: sensory; vision
    • 3. Oculomotor Nerves: motor; eye movement; pupils
    • 4. Trochlear Nerves: motor; eye movement
    • 5. Trigeminal Nerves: both; largest cranial nerve; three divisions: ophthalmic, maxillary, mandibular
    • 6. Abducens Nerves: motor; abducts eyes
    • 7. Facial Nerves: both; five major branches on face: temporal, zygomatic, buccal, mandibular, cervical
    • 8. Vestibulocochlear Nerves: sensory; equilibrium
    • 9. Glossopharyngeal Nerves: both; tongue and pharynx; taste, touch, pressure, pain
    • 10. Vagus Nerves: both; viscera, heart, lungs
    • 11. Accessory Nerves: motor; move head and neck
    • 12: Hypoglossal Nerves: motor; tongue for swallowing and speech
  5. Anatomy of the Ear
    • The Outer Ear:
    • Composed of:
    • • The auricle (pinna); helps direct sounds
    • • External acoustic meatus: contains hairs, sebaceous glands, and ceruminous glands
    • • Tympanic membrane: "ear drum"; forms the boundary between the external and middle ear

    • The Middle Ear:
    • Composed of
    • • The tympanic cavity; a small, air-filled space located within the petrous portion of the temporal bone; Medial wall is penetrated by Oval window and the Round window
    • Pharyngotympanic tube (auditory or eustachian tube); links the middle ear and pharynx
    • Ear ossicles—smallest bones in the body
    • 1. Malleus—attaches to the eardrum
    • 2. Incus—between the malleus and stapes
    • 3. Stapes—vibrates against the oval window
    • Tensor tympani and stapedius: Two tiny skeletal muscles in the middle ear cavity

    • The Inner Ear:
    • • Bony labyrinth—a cavity consisting of three parts:
    • 1. Semicircular canals
    • 2. Vestibule
    • 3. Cochlea
    • • Bony labyrinth is filled with perilymph; continuous with cerebrospinal fluid
    • • Membranous labyrinth: series of membrane-walled sacs and ducts; Fits within the bony labyrinth
    • - Consists of three main parts:
    • 1. Semicircular ducts
    • 2. Utricle and saccule
    • 3. Cochlear duct

    • Membranous labyrinthis filled with a clear fluid—endolymph
    • Outer Layer of the Eye
    • Composed of two regions of connective tissue:
    • • Sclera—posterior five-sixths of the tunic; white, opaque region; provides shape and an anchor for eye muscles
    • • Cornea—anterior one-sixth of the fibrous tunic
    • • Limbus—junction between sclera and cornea
    • • Scleral venous sinus—allows aqueous humor to drain

    • Vascular Layer
    • The middle coat of the eyeball
    • Composed of choroid, ciliary body, and iris
    • Choroid—vascular, darkly pigmented membrane; Forms posterior five-sixths of the vascular tunic; Brown color—from melanocytes; Prevents scattering of light rays within the eye
    • **Choroid corresponds to the arachnoid and pia maters
    • Ciliary body—thickened ring of tissue, which encircles the lens
    • Composed of
    • Ciliary muscle – smooth muscle
    • Ciliary processes— folds between muscle and zonule
    • Ciliary zonule (suspensory ligament); attached around entire circumference of the lens

    • Iris--visible colored part of the eye (pigmented)- attached to the ciliary body; composed of smooth muscle
    • *pupil: the round, central opening
    • Retina—the deepest tunic
    • Composed of two layers
    • • Pigmented layer—single layer of melanocytes
    • •Neural layer—sheet of nervous tissue
    • - Contains three main types of neurons
    • 1. Photoreceptor cells: rods and cones
    • 2. Bipolar cells
    • 3. Ganglion cells

    • • Photoreceptor cells signal bipolar cells
    • • Bipolar cells signal ganglion cells to generate nerve impulses
    • • Axons from ganglion cells run along internal surface of the retina
    • • Converge posteriorly to form the optic nerve
  6. Composition of Blood
    • Blood:
    • Contains both cellular and liquid components
    • Is a specialized type of connective tissue in which blood cells, called formed elements, are suspended in a fluid called plasma.

    • Centrifugation:
    • Heavier formed elements are packed down
    • Less dense plasma remains at the top

    • *Red mass at bottom: erythrocytes (red blood cells)% of blood volume that consists of erythrocytes =hematocrit (~45%)
    • *thin, gray layer in the middle: buffy coat (contains leukocytes (white blood cells) and platelets orthrombocytes (cell fragments that help stop bleeding)) ~1%
    • *Plasma = ~55%

    • Blood Plasma
    • Straw colored, sticky fluid
    • ~90% water
    • Contains over 100 different kinds of molecules:ions (like Na+ and Cl-)
    • nutrients (simple sugars, amino acids, lipids)
    • wastes (urea, ammonia, carbon dioxide)
    • oxygen, hormones, and vitamins

    • Plasma also contains 3 types of proteins:
    • 1. albumin: helps keep water from diffusing out of the bloodstream
    • 2. globulins: include both antibodies and the blood proteins that transport lipids, iron, and copper
    • 3. fibrinogen: one of several molecules involved in blood clotting

    • Formed Elements, or blood cells
    • erythrocytes, leukocytes, and platelets

    • neither erythrocytes nor platelets are true cells:
    • - lack nuclei and organelles; re just cell fragments
    • - cannot divide, survive only a few hours to months
    • Erythrocytes:
    • Special structural characteristics:
    • 1. biconcave shape: provides 30% more surface area than spherical
    • 2. over 97% hemoglobin (discounting water): contain lots of oxygen
    • 3. lack mitochondria; generate energy anaerobically- efficient O2 transporters also picks up 20% of CO2 transported by the blood

    • Leukocytes:
    • five types, divided into two groups based on presence or absence of membrane-bound cytoplasmic granules
    • Granulocytes: (neutrophils, eosinophils, and basophils) contain many obvious granules; much larger and much shorter lived than erythrocytes; have nonspherical nuclei and purple staining lobes;functionally all phagocytic
    • Agranulocytes: (lymphocytes and monocytes) lack obvious granules

    From most abundant to less abundant cell type:Never Let Monkeys Eat Bananas
  7. Structure of Blood Vessels
    • Composed of three layers (tunics):
    • 1. Tunica intima— internal layer, in contact with lumen; composed of simple squamous epithelium (endothelium); forms a smooth surface that minimizes friction of blood moving across them
    • 2. Tunica media—sheets of circularly arranged smooth muscle, with elastin and collagen fibrils in between; thicker in arteries than veins
    • • Contraction causes vasoconstriction
    • • Relaxation causes vasodilation
    • *both regulated by vasomotor nerve fibers of sympathetic nervous system
    • 3. Tunica externa—composed of connective tissue with elastin and collagen fibers; fibers run longitudinally (protects the vessels and anchors it to surrounding structures)
  8. Arteries of the Aortic Arch
    Head and Neck
    • Common carotid artery: Ascend through the neck, lateral to trachea; supply most parts of the head and neck; branch off into internal and external carotid arteries
    • Internal carotid arteries: supply the orbits and most of the cerebrum
    • External carotid arteries: supply most tissues of the head external to the brain and orbit
    • Brachiocephalic trunk: arise from aortic arch; split into right common carotid and right subclavian arteries
    • Subclavian artery:
    • Vertebral arteries: supply the posterior brain, vertebrae and cervical spinal cord; arise from subclavian arteries at the root of the neck
  9. Arteries of the Upper Limbs
    • **Arise from Subclavian Artery
    • Axillary artery: when the subclavian artery enters the axilla; branches into 4 arteries that supply the muscles of the chest and shoulder
    • Brachial artery: when the axial artery continues into the arm; descends medial to humerus; supplies anterior arm muscles; splits into the radial and ulnar arteries
    • Radial artery: supplies muscles of lateral anterior forearm and wrist, and thumb and index fingers
    • Ulnar artery: supplies muscles that cover the ulnar, splits into interosseous arteries that supply extensor and flexor muscles
    • Deep Palmar Arch: lies against the metacarpal bones, where radial and ulnar branches join; branch into digital arteries
    • Superficial palmar arch: underlies the skin and fascia of the hand
  10. Arteries of the Abdomen
    • Celiac Trunk: supplies the visceral in the superior part of the abdominal cavity; emerges from aorta at T12, divides into left gastric, splenic, and common hepatic arteries
    • Left Gastric artery: runs superiorly and to the left, to junction of stomach and esophagus, extends along the lesser curvature of the stomach
    • Splenic artery: runs horizontally and to the left, posterior to the stomach to enter the spleen; also supplies pancreas
    • Common Hepatic artery: the only branch of the celiac trunk that runs to the right; branches into the hepatic artery proper supplying the liver, the right gastric artery supplying the lesser curvature of the stomach, and the gastroduodenal artery supplying the greater curvature of the stomach, duodenum, and pancreas
    • Superior mesenteric artery: serves most of the intestines; arises from the abdominal aorta behind the pancreas
    • Renal arteries: stems from the sides of the aorta; paired arteries to the kidneys, aids in removing nitrogenous wastes
    • Gonadal arteries: paired arteries to the gonads; branch from aorta at L2, in between superior and inferior mesenteric arteries
    • Inferior mesenteric artery: the final major branch of the abdominal aorta; serves distal half of large intestine
  11. Arteries of the Lower Limb
    • Common iliac artery: aorta split from the level of L4, supply the inferior part of the anterior abdominal wall, pelvic organs, and lower limbs
    • External iliac artery: carry blood to the lower limbs; originates from common iliac arteries, branches slightly to anterior abdominal wall; becomes femoral artery as it enters the leg
    • Internal iliac artery: supply the pelvic walls, pelvic viscera, buttocks, medial thighs, and perineum
    • Femoral artery: descends vertically, medial to the femur; supplies thigh muscles
    • Popliteal artery: inferior continuation of the femoral artery; split inferiorly to form anterior and posterior tibial arteries
    • Anterior tibial artery: runs through anterior muscular compartment of the leg; supplies extensor muscles; becomes the dorsalis pedis artery at the ankle, and thearcuate atery at the base of the metatarsals, which branch off to form metatarsal arteries
    • Posterior tibial artery: descends through posteromedial part of the leg, deep to the soleus muscle; branches into fibular artery; supplies the flexor muscles
    • Fibular artery: descends medially along the fibula; helps supply the flexor muscle